[jvm-packages] Add DeviceQuantileDMatrix to Scala binding (#7459)

jvm-packages/xgboost4j-gpu/src/main/java/ml/dmlc/xgboost4j/gpu/java/CudfColumn.java

@@ -27,7 +27,7 @@ import ml.dmlc.xgboost4j.java.Column;
  * This class is composing of base data with Apache Arrow format from Cudf ColumnVector.
  * It will be used to generate the cuda array interface.
  */
-class CudfColumn extends Column {
+public class CudfColumn extends Column {
 
   private final long dataPtr; //  gpu data buffer address
   private final long shape;   // row count